Calculations related to coal blending

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It is reasonable to mix coals when closing positions, and it is scientific and feasible to do so according to the different needs of users. Coal blending is not a simple act of mixing; rather, it involves adjusting the various properties of the coal based on an accurate understanding of those properties, in order to meet the needs of the enterprise. 1. The calculation of the moisture content (Mad) of blended coal is carried out using the conventional weighted average method. That is, the Mad value of each individual coal type is multiplied by its corresponding proportion; the sum of these products is then divided by the sum of the proportions of all individual coal types, thereby yielding the Mad value for the blended coal: Blended coal Mad% = ∑÷∑ (proportions of coal types A, B, C, etc.). The principle of the above formula also applies to calculating other indicators such as Aad, Vad, St,ad for coal blending. 2. Calculation of the ash on a dry basis for blended coal (Ad): Since each individual coal type in the blend is proportioned based on its value on an air-dried basis, in order to determine the ash content on a dry basis for the blended coal, it is necessary first to convert the proportions of each individual coal type into those corresponding to dry coal, before applying the weighted average method to calculate the Ad value for the blended coal. That is, the proportion of dry coal equals the proportion of coal with moisture removed by air multiplied by (100–Mad)/100. Therefore, the theoretical Ad value for coal blending should be calculated using the following formula: Coal blending Ad% = ∑÷∑ (the dry basis proportions of various individual coals such as A, B, C, etc.). 3. Calculation of dry ash-free basis volatile matter (Vdaf): The principle is the same as that used for calculating the ash content on a dry basis for blended coals. When determining the theoretical Vdaf of a blended coal, it is also necessary to first convert the proportions of each individual coal type into those on a dry ash-free basis before performing the weighted calculation. That is, the ratio of dry ash-free base coal equals the ratio of coal with air-dried moisture multiplied by 100 – Mad – Aad100. Therefore, the theoretical Vdaf value for blended coal should be calculated using the following formula: Blended Coal Vdaf% = ∑÷∑ (the dry ash-free proportions of various individual coals). 4. Calculation of volatile matter on a received basis (Var): When calculating the volatile matter of blended coal on a received basis, it is first necessary to convert the proportions of each individual coal into proportions corresponding to coal with all its moisture content, and then the theoretical Var value for the blended coal can be determined using the conventional weighted average method. The calculation formula is as follows: Var% of blended coal = ∑(percentage of analytically determined water content in each individual coal type) × (100 – Mad) × (100 – Mt) / ∑(percentage of analytically determined water content in each individual coal type) × (100 – Mad) × (100 – Mt). 5. Calculation of the lower heating value of blended coal on a received basis (Qnet,ar): The principle for calculating Qnet,ar for blended coal is the same as that used to calculate the Var value for such coal. (1) First, convert the proportions of analytically determined moisture in each coal type to proportions based on the received basis using the following formula: Proportion on received basis for each coal type% = Proportion on analytical basis for each coal type% × (100 – Mad) × (100 – Mt). (2) Calculate: ∑(Proportion on received basis for each coal type × Qnet,ar) ÷ ∑Proportion on received basis for each coal type. 6. Calculation of the ash fusion characteristic temperatures (DT, ST, FT) for blended coals: Since the ash content varies among different individual coals, it is necessary to take into account the ash yield of each coal when calculating the theoretical ash fusion characteristic temperatures for blended coals. The specific calculation formula is as follows: ST, FT, or DT (°C) of the blended coal = ∑÷∑. 7. Additivity of ash components in blended coal: When calculating the ash composition of blended coal, it is also necessary to take into account the differences in the ash content of each individual coal type. Therefore, the composition of coal blending ash should be calculated using the following formula. The % of SiO2, Al2O3, etc. in the blended coal = ∑÷∑. It is to be reiterated that blending coal does not constitute fraud; anyone who uses this method to cheat will bear full responsibility for it!